SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b04b346874ae37043de57de816dc9b792ca05c2688e49951dc2321d7cf3561b2' 
  AND token = 'C//rjc3QwROsFmGRMj9zKc8xvMAqdLVHKcN5D3Is+OQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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