SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831107f826a44ea083bc330da8cd8a2075b44fa4d53f0b08139df4f8f6d407b6' 
  AND token = '71LQrCYuENQ5O6KWdFNuSqWF+lhHEoPQ6C6Hvrgtuk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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