SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b08eebcf195988551de9af2b52ba637b6f5148a9fc244dd6b0d72aa3bc60166c' 
  AND token = '8+Ea3n6SFdDrUN0/HqsGgdoBD7ph8uUkljAU1rYPpQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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