SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6edff4b51bbfd1e74c1023e82c308856689e90a028d00befb5f624e7a7c1226e' 
  AND token = 'Qt1I9nYnurOmLBvohQq+Rd9FPcZPMK/Yz3WgUgpEdIY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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