SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03dc49857fc249c633bde534b80a7a5152fe3058143d721e4c9d440c51534213' 
  AND token = 'M3XQtNaOehqPK5evIvy8RIHjXF13XrbL1KfYtidBLp4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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