SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5399af4ed4a44ab957af6b0e286763e9826aa830e752be5643e355a5f034143' 
  AND token = 'u5sLW4cRw5CL0QD6qpcwowJHyLslHDrH3wt1C0+5R7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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