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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18fd8cddb7cc9b4d3e42017781d2ff95a086aecb8f2ee40c7896826fc30220bf' 
  AND token = 'kk7r4O1R+KIjMHK3xhNU+nKm3Zkq2qtWFBYy5RUdaUw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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