SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97c1ef13da22c61f90f24ea8b489f2a21041b7a918477bffd28febb029d8fdf2' 
  AND token = 'U3ZF3NNpLT0OuxDaIbz/j5UCCxXsDpwXhypYbjxlEJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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