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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b719c571902ed9a2e069b148e46a10279618dad9a063c284df93e7ba86b2471d' 
  AND token = 'K0bLnB4WTnL9//cR9leBdMiARAAuPpHWvQgybRPyEVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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