SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ccc808bc47004e71dde7a0ff03542c9240c351d7600fd50b51d7a619e0dbcab' 
  AND token = 'clxCmeBlOCcgOS/a1oItqYP01H4Sm+5NNNs8y1XUuzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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