SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff658db58e162e482479f9505cb8de2522a8e50bfcf87df074d02e85ea66a1a8' 
  AND token = '1/Jr1iI3j3JtF+GLMpM3k0mkPIE2G5NQPqBpBZUKOsA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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