SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75363e250fd2cbd2f6c5d2258289c550167f169d256f487f8f26f75b844c3117' 
  AND token = 'nxMOKYUgJIBI4ohvAVOnVb49M+xmtsdlp1sbULojnnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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