SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c7ea35aa003704479603fd47a2999b6634fe5871f562a1711570c9d22186b1' 
  AND token = 'GPgk971xmdjt6DwpulJve2tHDVDzddzwaBUsAIf82XY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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