SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec2b426498c0ba0137b6c8138c8dfcfb7cb702d13d1ed093e1a898f61f434173' 
  AND token = '6zoi0lyBm6tS6nvjMFOEqGKZRVPPI71Kgem/lORpSFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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