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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f5f631920f2d53697e7848b06cbf2ac97b5ad08d728d0cc05c66f1cd28de5508' 
  AND token = 'rcQ1MhVV9WhTgf7GtQkcEeUzdS0uXkoG1XniQ4FoMPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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