SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1a87fa3fa582817af1d445122d51eaecf2d848df23ee7a5327b5094dae90797' 
  AND token = '8jhmbMBPUChHu6fCIlhfm1i6+YoftMjtIDEO4rWLmX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}