SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68c4b22ad574e693c7707f523e9d50bf20aa00e760df2457762779182b854b02' 
  AND token = 'KUGcNy4HoCPgDF8SVCsCnKUO4fEl34Mbnw6GeAm3j5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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