SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa39786ae9426a02f4c4361c105667ae751633ffabc80b1b7cdd60fb6ca283a3' 
  AND token = '+/nDDRBBJ1BrDvmh4QVmwHN6pRgur1RyRRkCmg+39bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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