SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55ea64b25d4c37b70f379a078adcc877406b62bfdd6056595030b0424c632d49' 
  AND token = 'aaXHanCTjom+FnMr8/vcf+BBaZqCEEpf18CLN5Zdns0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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