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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c51fd9930573b043a3b69bd542e4c24f89fdc9d4e257b66d654ebb7b7fcd3fef' 
  AND token = 'Ii+ZOmoyXzWiTqsLR515AXq5zZTJQJiu/VdKzi0mosY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}